Method for improved production of cyanophycin and secondary products thereof

Abstract

The present invention relates to a thermostable cyanophycin synthetase produced from Synechococcus elongatus and to a method for improved production of cyanophycin and/or secondary products thereof.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a thermostable cyanophycin synthetase, to transformed organisms containing such an enzyme and to a method for improved production of cyanophycin and/or secondary products thereof, for example polyaspartic acid or arginine.

BACKGROUND OF THE INVENTION

[0002] Multi-L-arginyl-poly-L-aspartate (cyanophycin) is a branched polypeptide which contains aspartic acid and arginine in the ratio of 1:1. The chemical structure corresponds to a poly-.alpha.-aspartate backbone with arginine side radicals which are linked via peptide bonds to virtually all .beta.-carboxyl groups of the backbone. DE-A 198 25 509 describes the identification, cloning and heterologous expression of the gene for cyanophycin synthetase from Synechocystis PCC 6803. The enzyme activity is determined here by means of a radioactive assay in which L-[U-.sup.14C]-arginine is incorporated into cyanophycin from Aphanocapsa PCC 6308, introduced as primer. The enzyme reaction itself takes place at 28.degree. C. here.

[0003] DE-A 197 09 024 discloses the extraction and purification of cyanophycin from Aphanocapsa PCC 6308, the synthesis being carried out at 20.degree. C.

[0004] DE-A 198 13 692 merely discloses isolation of the cyanophycin synthetase gene from Synechocystis PCC 6803 or Anabaena variabilis ATCC 29 413. Technical aspects of cyanophycin production, however, are not described here.

[0005] FEMS Microbiology Letters 181 (1999) 229-236 discloses the production of cyanophycin using Synechococcus sp. MA 19.

[0006] A disadvantage of large-scale cyanophycin production according to the known methods is that, for optimal product yield, a relatively narrow temperature range, normally below 35.degree. C., should not be exceeded.

[0007] This represents a considerable restriction in the degrees of freedom for large-scale production within the process control for the production of cyanophycin, since higher temperatures from the outset prevent contamination by foreign cultures.

[0008] Therefore production of cyanophycin also at substantially higher temperatures than previously described, in combination with higher flexibility in process control and considerably improved product yields is desirable, in order to isolate therefrom the secondary products such as polyaspartic acid or arginine on a large scale.

[0009] This object is achieved by the present invention.

SUMMARY OF THE INVENTION

[0010] The present invention relates to a cyanophycin synthetase which is distinguished by having a temperature optimum in the range of >35.degree. C. and an amino acid sequence according to SEQ ID No: 01, encoded by an isolated nucleotide sequence according to SEQ ID No: 02, an allele, homologue or derivative of this nucleotide sequence or a nucleotide sequence hybridizing therewith.

[0011] In a preferred variant of the present invention, the cyanophycin synthetase of the invention has a temperature optimum in the range from 35.degree. C. bis 55.degree. C., preferably in the range from 35.degree. C. bis 50.degree. C.

[0012] The cyanophycin synthetase is further distinguished by the fact that it originates from Synechococcus elongatus. The cyanophycin synthetase of the invention represents a thermostable enzyme.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a representation of the chemical structure of the synthetic peptide primers used for synthesis of cyanophycin by means of cyanophycin synthetase.

[0014] FIG. 2 is a representation of the results of an SDS polyacrylamide gel electrophoresis (SDS-PAGE) for in vitro synthesis of cyanophycin-like material by means of purified cyanophycin synthetase.

[0015] FIG. 3 is a representation of the results of an SDS-PAGE for chain elongation of a primer by means of cyanophycin synthetase at the C-terminal end of the peptide primer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0016] The present invention relates to a cyanophycin synthetase which is distinguished by having a temperature optimum in the range of >35.degree. C. and an amino acid sequence according to SEQ ID No: 01, encoded by an isolated nucleotide sequence according to SEQ ID No: 02, an allele, homologue or derivative of this nucleotide sequence or a nucleotide sequence hybridizing therewith.

[0017] In a preferred variant of the present invention, the cyanophycin synthetase of the invention has a temperature optimum in the range from 35.degree. C. bis 55.degree. C., preferably in the range from 35.degree. C. bis 50.degree. C.

[0018] The cyanophycin synthetase is further distinguished by the fact that it originates from Synechococcus elongatus. The cyanophycin synthetase of the invention represents a thermostable enzyme.

[0019] The present invention also relates to isoenzymes of the cyanophycin synthetase of the invention. These isoenzymes mean enzymes having identical or comparable substrate specificity and action specificity, but having a different primary structure. In addition, the present invention also includes modified forms of cyanophycin synthetase. According to the invention, these mean enzymes in which alterations are present in the sequence, for example at the N and/or C termini of the polypeptide or in the region of conserved amino acids, which alterations, however, do not impair the function of the enzymes. These modifications may be carried out by exchanging one or more amino acids according to known methods.

[0020] A particular embodiment of the present invention includes variants of the inventive cyanophycin synthetase, whose substrate specificity, for example, was altered, for example with regard to the production of polyaspartic acid, by the amino acid exchange, compared with the particular starting protein. The same is true for the stability of the enzymes of the invention in cells; for example, the enzymes have increased or reduced sensitivity towards degradation by proteases.

[0021] The present invention further relates to polypeptides with cyanophycin synthetase function, whose amino acid sequence has been altered such that they are insensitive to regulatory compounds, for example to the metabolic endproducts regulating their activity (feedback insensitive).

[0022] An isolated nucleotide sequence or an isolated nucleic acid fragment means, according to the invention, an RNA or DNA polymer which may be single- or double-stranded and may optionally contain natural, chemically synthesized, modified or artificial nucleotides. The term "DNA polymer" here also includes genomic DNA, cDNA or mixtures thereof.

[0023] According to the invention, alleles mean functionally equivalent nucleotide sequences, i.e. nucleotide sequences with essentially identical action. Functionally equivalent sequences are those sequences which, despite deviating nucleotide sequences, for example due to the degeneracy of the genetic code, still retain the desired functions. Functional equivalents thus include naturally occurring variants of the sequences described herein and also to artificial nucleotide sequences obtained, for example, by chemical synthesis and, where appropriate, adjusted to the codon usage of the host organism. Moreover, functionally equivalent sequences include those having a modified nucleotide sequence which confers on the enzyme insensitivity or resistance to inhibitors, for example.

[0024] A functional equivalent means in particular also natural or artificial mutations of an originally isolated sequence which continue to show the desired function. Mutations include substitutions, additions, deletions, exchanges or insertions of one or more nucleotide residues. Also included here are "sense mutations" which can lead at the protein level to the exchange of conserved amino acids, for example, but not to any fundamental change in the protein activity and thus are functionally neutral. This also includes modifications of the nucleotide sequence which, at the protein level, concern the N or C terminus of a protein but with no substantial restriction of protein function. These modifications may even have a stabilizing influence on the protein structure.

[0025] The present invention further also includes those nucleotide sequences which are obtained by modification of the nucleotide sequence, resulting in corresponding derivatives. The aim of such a modification may be, for example, the further narrowing down of the coding sequence contained therein or else, for example, the introduction of further recognition sites for restriction enzymes. Functional equivalents are also those variants whose function, compared with the starting gene or gene fragment, is reduced or enhanced.

[0026] In addition, the present invention relates to artificial DNA sequences, as long as they provide the desired properties, as described above, and can be inserted into or appended to the gene of the cyanophycin synthetase of the invention. It is possible, for example, to determine such artificial DNA sequences by translating back from proteins generated by means of computer-assisted programs (molecular modelling) or by in vitro selection. Coding DNA sequences which have been obtained by translation back from a polypeptide sequence according to the codon usage specific for the host organism are particularly suitable. It is possible for a skilled worker familiar with molecular genetic methods readily to determine the specific codon usage by computer analyses of other, already known genes of the organism to be transformed.

[0027] According to the invention, homologous sequences mean those which are complementary to the nucleotide sequences of the invention and/or hybridize with these sequences. The term "hybridizing sequences" includes, according to the invention, substantially similar nucleotide sequences from the group comprising DNA or RNA, which specifically interact with (bind to) the abovementioned nucleotide sequences under known stringent conditions. This also includes short nucleotide sequences of, for example, from 10 to 30, preferably from 12 to 15 nucleotides in length. According to the invention, "nucleotide primers" or probes are inter alia also included here.

[0028] According to the invention, the sequence regions preceding (5' or upstream) and/or following (3' or downstream) the coding regions (structural genes) are also included. In particular, sequence regions with regulatory function are included here. They can influence transcription, RNA stability or RNA processing and also translation. Examples of regulatory sequences are inter alia promoters, enhancers, operators, terminators or translation enhancers.

[0029] Operative linkage means the sequential arrangement of, for example, promoter, coding sequence, terminator and, where appropriate, further regulatory elements, such that each of the regulatory elements can fulfil its predetermined function when the coding sequence is expressed. These regulatory nucleotide sequences may be of natural origin or can be obtained by chemical synthesis. A suitable promoter is in principle any promoter which is able to control gene expression in the appropriate host organism. According to the invention, the said promoter may also be a chemically inducible promoter which makes it possible to control at a particular time expression of the genes subject to it in the host cell. By way of example, mention may be made here of a promoter inducible by IPTG (isopropyl .beta.-thiogalactopyranoside).

[0030] A gene construct is prepared by fusion of a suitable promoter with the nucleotide sequence of the invention, according to common recombination and cloning techniques known from the literature. The DNA fragments can be linked to one another by attaching adapters or linkers to the fragments.

[0031] Moreover, the present invention relates to a vector comprising at least one nucleotide sequence of the type described above coding for a cyanophycin synthetase specific for producing cyanophycin, regulatory nucleotide sequences operatively linked to the said nucleotide sequence and also additional nucleotide sequences for selection of transformed host cells, for replication within the host cell or for integration into the appropriate host cell genome. The vector of the invention may further comprise a gene construct of the abovementioned type.

[0032] Suitable vectors are those which are replicated in micro-organisms such as, for example, bacteria, fungi and/or plants. Examples of known vectors are pBluescript (Stratagene, 11099 North Torney Pines Rd., La Jolla, Calif. 92 037, USA) or pET (Novagen, 601 Science Drive, Madison, WJ 53 711, USA). This list, however, is non-limiting for the present invention.

[0033] Utilizing the nucleic acid sequences of the invention, it is possible to synthesize and use appropriate probes or else nucleotide primers for the purpose of amplifying and isolating analogous genes from other unicellular or multicellular organisms, preferably bacteria, fungi, algae or plants, for example with the aid of the polymerase chain reaction ("PCR") technique.

[0034] The present invention thus also relates to a probe for identifying and/or isolating genes coding for proteins involved in cyanophycin biosynthesis, preferably further thermostable cyanophycin synthetases; this probe is prepared starting from the inventive nucleic acid sequences of the type described above and contains a label suitable for detection. The probe may be a section of the sequence of the invention, for example from a conserved region, which is, for example, from 10 to 30 or, preferably, 12 to 15 nucleotides in length and which can hybridize specifically with homologous nucleotide sequences under stringent conditions. Suitable labels are known from the literature in large numbers.

[0035] The present invention further relates to the transfer of the inventive nucleic acid sequence or a part thereof, coding for a cyanophycin synthetase, an allele, homologue or derivative thereof, or of a nucleotide sequence hybridizing with these sequences into a heterologous host system. This also includes the transfer of a gene construct or vector of the invention into a heterologous host system.

[0036] According to the invention, a heterologous host system means a unicellular or multicellular organism. Examples of these are micro-organisms, fungi, lower or higher plants, tissue or cells thereof. According to the invention, preference is given to bacteria, particularly preferably of the genus of enterobacteria and, in particular, of the species Escherichia coli. Furthermore, useful plants such as potatoes or tobacco are particularly preferred.

[0037] The inventive nucleotide sequence coding for an inventive thermostable cyanophycin synthetase is transferred into one of the abovementioned host systems according to known methods. Examples of methods for DNA transfer into suitable host systems, which may be mentioned, are transformation, electroporation, conjugation and agrobacteria-mediated DNA transfer or particle bombardment. This list serves only the purpose of illustrating the present invention and is non-limiting.

[0038] A transformed unicellular or multicellular organism resulting from a successful nucleic acid transfer thus differs from the corresponding untransformed organism by containing and being able to express additional nucleic acids of the inventive type.

[0039] The invention thus also relates to a transformed unicellular or multicellular organism comprising a cyanophycin synthetase of the invention and/or a vector comprising a cyanophycin synthetase of the type described above.

[0040] The present invention further relates to a method for providing an inventive cyanophycin synthetase of the type described above, in which method the nucleotide sequence coding for the enzyme is isolated from a thermophilic unicellular or multicellular organism, is, where appropriate, operatively linked to regulatory structures and/or cloned into a vector suitable for heterologous expression, is, where appropriate, transferred into a heterologous host system, is expressed there and is finally isolated from this host system and, where appropriate, purified and/or concentrated.

[0041] Direct isolation of an amount of cyanophycin synthetase which is sufficient for cyanophycin synthesis, from a thermophilic organism, without prior concentration in a heterologous system, is also conceivable. Furthermore, it is then possible to use the inventive cyanophycin synthetase enzyme, for example in an in vitro system for synthesizing cyanophycin and/or secondary products thereof.

[0042] The present invention also relates to a method for producing cyanophycin and/or secondary products thereof, in which a cyanophycin synthetase and/or a vector and/or a transformed unicellular or multicellular organism of the type described above are used. However, the present invention includes not only the production of cyanophycin and/or secondary products thereof in a living host system but also the in-vitro synthesis of cyanophycin with the aid of an isolated cyanophycin synthetase of the type described above.

[0043] The inventive method for producing cyanophycin is distinguished by carrying out the enzyme-catalyzed synthesis in a temperature range from 35.degree. C. to 55.degree. C., preferably in a range from 35.degree. C. to 50.degree. C.

[0044] The method of the invention is advantageously distinguished by the fact that, owing to the wide temperature range, the process is less error-prone, in particular above 28.degree. C., allows greater variability in process control and thus provides improved product yield. Thus, the inventive production of cyanophycin and/or secondary products thereof is substantially more reproducible and economical than the hitherto known methods.

[0045] At the molecular level, the cyanophycin synthetase of the invention catalyses an ATP-dependent chain elongation. Surprisingly, the enzyme has two active (catalytic) centres. The cyanophycin synthetase of the invention stepwise and alternately (sequentially) incorporates one aspartic acid molecule and subsequently one arginine molecule into a cyanophycin precursor (peptide primer). Without a primer, the enzyme-catalysed chain elongation cannot be started. Studies thereon are depicted in FIG. 2.

[0046] Referring now to FIG. 2 there is illustrated a representation of the results of an SDS polyacrylamide gel electrophoresis (SDS-PAGE) for in vitro synthesis of cyanophycin-like material by means of purified cyanophycin synthetase. The reaction mixture contains inter alia about 10 .mu.M Primer (.beta.-Asp-Arg).sub.3. After incubation for 24 hours at room temperature, aliquots of the reaction mixture are analysed by means of SDS-PAGE and proteins are visualized according to standard methods. The lanes illustrate the following: Lane 1: complete reaction mixture; lane 2: reaction mixture without aspartic acid; lane 3: reaction mixture without arginine; lane 4: reaction mixture without ATP; lane 5: reaction mixture without primer (.beta.-Asp-Arg).sub.3; lane 6: reaction mixture with heat-inactivated enzyme (5 min, 100.degree. C.). The protein band above the 97.4 kDa standard represents cyanophycin synthetase. The diffuse bands below 29 kDa in lanes 1, 2 and 3 represent cyanophycin-like material.

[0047] The chemical structure of various primers used in the synthesis of cyanophycin is depicted in FIG. 1. This clearly indicates that incorporation takes place exclusively at the C-terminal end of the precursor and only if both amino acids, i.e. aspartic acid and arginine or another basic amino acid, are present together. A summary of these studies is depicted in FIG. 3 and Table 1.

[0048] Referring now to FIG. 3 there is illustrated a representation of the results of an SDS-PAGE for chain elongation of a primer by means of cyanophycin synthetase at the C-terminal end of the peptide primer. Various primers (FIG. 1) are added to the reaction mixture. After incubation of the reaction mixtures for 24 hours at room temperature, aliquots of the reaction mixture are analysed by means of SDS-PAGE and proteins are visualized according to standard methods. The lanes illustrate the following: lane 1: mixture without primer; lane 2: mixture with about 8 .mu.M unprotected primer (.beta.-Asp-Arg).sub.3; lane 3: mixture with about 8 .mu.M N-terminally protected primer (.epsilon.-Ahx.sub.2-(.beta.-Asp-Arg).sub.3); lane 4: mixture with about 8 .mu.M C-terminally protected primer ((.beta.-Asp-Arg).sub.3-.epsilon.-A- hx.sub.2); lane 5: as lane 4 but with about 160 .mu.M primer. The diffuse bands below 29 kDa in lanes 1, 2 and 3 represent cyanophycin-like material. Table 1 below illustrates the cyanophycin synthetase-catalysed incorporation of L-aspartic acid (Asp) and L-arginine (Arg) into synthetic peptide primers.

1TABLE 1 No. Primer Substrate(s) Product C-terminally blocked primer: (1) (.beta.-Asp-Arg).sub.3-.epsilon.-Ahx.sub.2 Asp + Arg none (2) (.beta.-Asp-Arg).sub.3-.epsilon.-Ahx.sub.2 Asp or Arg none N-terminally blocked primer: (3) .epsilon.-Ahx.sub.2-(.beta.-Asp-A- rg).sub.3 Asp + Arg Cyanophycin (4) .epsilon.-Ahx.sub.2-(.beta.-Asp- -Arg).sub.3 Asp .epsilon.-Ahx.sub.2-(.beta.-Asp-Arg).sub.3-Asp (5) .epsilon.-Ahx.sub.2-(.beta.-Asp-Arg).sub.3 Arg none Unblocked primers: (6) (.beta.-Asp-Arg).sub.3 Asp + Arg Cyanophycin (7) (.beta.-Asp-Arg).sub.3 Asp (.beta.-Asp-Arg).sub.3-Asp.sup.a) (8) (.beta.-Asp-Arg).sub.3 Arg none (9) (.beta.-Asp-Arg).sub.3 .beta.-Asp-Arg none (10) (.beta.-Asp-Arg).sub.3-Asp Asp + Arg Cyanophycin (11) (.beta.-Asp-Arg).sub.3-Asp Asp none (12) (.beta.-Asp-Arg).sub.3-Asp Arg (.beta.-Asp-Arg).sub.4 .sup.a)In principle, the reaction product could also be Asp-(.beta.-Asp-Arg).sub.3. However, this possibility is excluded due to the results using the N-terminally or C-terminally blocked primers (reactions 2 and 4 of this table).

[0049] The present invention further relates to the use of a vector comprising an inventive cyanophycin synthetase of the abovementioned type for preparing a transformed unicellular or multicellular organism as described above. The present invention likewise includes the use of such a transformed unicellular or multicellular organism for producing an inventive cyanophycin synthetase and/or for producing cyanophycin and/or secondary products thereof. Moreover it is also possible to make use of a cyanophycin synthetase isolated according to the invention for in-vitro production of cyanophycin and/or secondary products thereof. In addition, the present invention relates to the use of cyanophycin and/or secondary products thereof for producing food supplements and/or compositions in the fields of agriculture and/or crop protection. Further fields of application for cyanophycin and/or secondary products thereof can be found in the paper, textile, pigment, paint, ceramics, building material or detergent industry and also in the fields of water and wastewater treatment.

[0050] The present invention is characterized in more detail by the following examples which are, however, not limiting for the invention:

[0051] General Genetic Methods:

[0052] DNA isolation, plaque hybridization, polymerase chain reaction (PCR), construction of a genomic DNA gene library and the procedures for protein analysis by means of SDS polyacrylamide gel electrophoresis (SDS-PAGE) including protein purification, as well as culturing of microorganisms such as, for example, Escherichia coli are carried out according to standard methods described in Sambrook, J. et al. (1998, Molecular Cloning: A Laboratory Manual; 2.sup.nd Edition, Cold Spring Harbor Laboratory Press, N.Y.) or according to information by the manufacturers. Blue-green algae such as, for example, Synechococcus elongatus were cultured according to descriptions in Yamaoka, T., et al. (1978, Plant Cell Physiol., 19: 943-954).

[0053] Peptide Primer Synthesis:

[0054] The branched peptide primers (.beta.-Asp-Arg).sub.3, (.beta.-Asp-Arg).sub.3-Asp, .epsilon.-Ahx.sub.2-(b-Asp-Arg).sub.3 and (.beta.-Asp-Arg).sub.3-.epsilon.-Ahx.sub.2 (see FIG. 1; Ahx=.epsilon.-aminohexane acid) were synthesized on a solid phase following Fmoc/tBu chemistry via O-(benzotriazol-1-yl)-N,N,N',N'-tetramet- hyluronium tetrafluoroborate activation using the building block Fmoc-Asp-[Arg(Pmc)-OtBu]-OH. The building block was prepared in solution by the following reaction sequence: (i) acylation of H-Arg(Pmc)-OtBu (Bachem Biochemicals) with Fmoc-Asp-All (All=allyl ester) (Novabiochem) using dicyclohexylcarbodiimide/N-hydroxybenzotriazole (Novabiochem) as activators and then (ii) opening of the allyl ester with the aid of N-methylaniline and tetrakis(triphenylphosphine)palladium(0) as catalyst. The synthesis is started on a resin loaded with Fmoc-Arg(Pmc)-TentaGel-S-- PHB (Rapp Polymere). The peptide primers are linked by the following reaction: (i) coupling of Fmoc-Asp-OtBu and subsequently (ii) attaching twice the building block Fmoc-Asp-[Arg-(Pmc)-OtBu]-OH. Furthermore, the N-terminally blocked peptide primer .epsilon.-Ahx.sub.2-(b-Asp-Arg).sub.3 was prepared by attaching Fmoc-.epsilon.-aminohexane acid (Novabiochem) twice to the resin-bound peptide primer described above. The finished peptides were deprotected by treatment with 94% trifluoroacetic acid, 1% phenol, 2% water, 3% triisobutylsilane and removed from the resin, the peptides and the N-terminally blocked peptide primers being obtained as free acids. The C-terminally blocked peptide primer (.beta.-Asp-Arg).sub.3-.epsilon.-Ahx.sub.2 was prepared on a TentaGel-SRAM resin (Rapp-Polymere) according to the following procedure: (i) two times coupling of Fmoc-.epsilon.-aminohexane acid and subsequently three times coupling of the building block Fmoc-L-Asp-[L-Arg(Pmc)-OtBu). The finished primer was removed as described above and gave the peptide as carboxamide.

[0055] The peptide primer (.beta.-Asp-Arg).sub.3-Asp was synthesized on a TentaGel-S-PHB resin (Rapp Polymere) loaded with Fmoc-Asp(OtBu) by attaching the appropriate building block three times. As described above the peptide was likewise removed from the resin and deprotected. The peptide was obtained as free acid here. All peptide primers were purified on a C-18 column (Vydac 201SP54) and analysed with the aid of RP HPLC and MALDI MS.

[0056] The dipeptide .beta.-Asp-Arg was likewise prepared on a TentaGel-S-PHB phase which had been loaded with Fmoc-Arg(Pmc) before. After the Fmoc protection group had been removed with 20% strength piperidine-DMF solution, the resin was treated with 4 eq (equivalents) of Boc-Asp-OtBu (Bachem Chemicals), 4 eq of O-(benzotriazol-1-yl)-N,N,N',N'-- tetramethyluronium tetrafluoroborate and 8 eq of diisopropyl-ethylamine in DMF. The peptide was removed from the resin with trifluoroacetic acid containing 1% phenol, 2% water and 3% triisobutylsilane, then precipitated with cold t-butylmethyl and finally purified on a C-18 column (Vydac 201SP54) and analysed by RP HPLC and MALDI MS.

[0057] Reaction Mixtures and Product Analysis:

[0058] The reaction mixtures for product analysis by means of mass spectrometry contain in a volume of 125 .mu.l the following components: 100 mM NH.sub.4HCO.sub.3 (pH 8.0), 4 mM ATP disodium salt, 20 mM MgCl.sub.2, 8 mM KCl, 2 mM DTT, 0.2 mM L-aspartic acid, 0.2 mM L-arginine, .gtoreq.10 .mu.M synthetic primers and 3 .mu.g of cyanophycin synthetase.

[0059] For product analysis by means of SDS-PAGE, 125 .mu.l of reaction mixture contain the following: 50 mM Tris-HCl (pH 8.0), 4 mM ATP disodium salt, 20 mM MgCl.sub.2, 20 mM KCl, 1 mM DTT, 0.8 mM L-aspartic acid, 0.4 mM L-arginine, .gtoreq.10 .mu.M synthetic primers and 3 .mu.g of cyanophycin synthetase.

[0060] The samples are incubated at room temperature for 10-14 hours and subsequently either mixed with sample buffer (SDS-PAGE) or frozen (mass spectrometry). The products are analysed by means of mass spectrometry (MALDI MS) according to the information in the user manual of the manufacturer (PerSeptive Biosystems).

[0061] Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be under stood as modified in all instance by the term "about."

[0062] Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Sequence CWU 1

1

2 1 896 PRT Synechococcus elongatus 1 Met Lys Ile Leu Lys Leu Gln Thr Leu Arg Gly Pro Asn Tyr Trp Ser 1 5 10 15 Ile Arg Arg His Lys Leu Ile Val Met Arg Leu Asp Leu Glu Glu Val 20 25 30 Ala Asn Thr Pro Ser Asn Gln Ile Ser Gly Phe Val Asp Gly Leu Val 35 40 45 Arg Val Leu Pro Ser Leu Tyr Asn His Phe Cys Ser Leu Gly His Glu 50 55 60 Gly Gly Phe Leu Thr Arg Leu Arg Glu Gly Thr Tyr Leu Gly His Val 65 70 75 80 Val Glu His Val Ala Leu Glu Leu Gln Glu Leu Ala Gly Met Pro Val 85 90 95 Gly Phe Gly Arg Thr Arg Glu Thr Ser Thr Pro Gly Val Tyr Gln Val 100 105 110 Val Tyr Glu Tyr Gln Val Glu Glu Ala Gly Arg Tyr Ala Gly Arg Ala 115 120 125 Ala Val Arg Leu Cys Gln Ser Ile Ile Asp Thr Gly Thr Tyr Pro Gln 130 135 140 Gln Glu Leu Asp Gln Asp Leu Ala Asp Leu Arg Glu Leu Lys Ala Lys 145 150 155 160 Ala Ser Leu Gly Pro Ser Thr Glu Ala Ile Val Arg Glu Ala Glu Ala 165 170 175 Arg Asn Ile Pro Trp Phe Glu Leu Ser Ser Arg Ser Ile Ile Gln Leu 180 185 190 Gly Tyr Gly Ala Arg Ser His Arg Met Gln Ala Thr Leu Ser Asp Arg 195 200 205 Ser Ser Ile Leu Ala Val Glu Leu Ala Ser Asp Lys Glu Gly Ala Lys 210 215 220 Arg Leu Leu Gln Asp Ala Gly Ile Pro Val Pro Lys Gly Thr Val Ile 225 230 235 240 Arg Tyr Ile Glu Asp Leu Pro Glu Ala Ile Glu Glu Ile Gly Gly Tyr 245 250 255 Pro Ile Val Ile Lys Pro Leu Asn Gly Asn His Gly Arg Gly Ile Thr 260 265 270 Ile Asp Ile Asn Ser Leu Glu Ala Ala Glu Glu Ala Phe Glu Ile Ala 275 280 285 Ser Ser Ile Ser Lys Ser Val Ile Val Glu Arg Tyr His Ala Gly Arg 290 295 300 Asp Phe Arg Val Leu Val Val Asn Gly Lys Val Val Ala Val Ala Glu 305 310 315 320 Arg Val Pro Ala His Val Ile Gly Asp Gly His Ser Thr Ile Glu Glu 325 330 335 Leu Ile Glu Lys Thr Asn Gln Asp Pro Gln Arg Gly Asp Gly His Asp 340 345 350 Asn Ile Leu Thr Arg Ile Glu Val Asn His Asp Thr Trp Thr Leu Leu 355 360 365 Glu Lys Gln Gly Tyr Thr Leu Asn Thr Val Leu Gln Pro Gly Glu Ile 370 375 380 Cys Tyr Leu Arg Ala Thr Ala Asn Leu Ser Thr Gly Gly Ile Ala Ile 385 390 395 400 Asp Arg Thr Asp Glu Ile His Pro Glu Asn Val Trp Ile Cys Gln Arg 405 410 415 Ala Ala Arg Ile Ile Gly Leu Asp Ile Ala Gly Ile Asp Val Val Ser 420 425 430 Pro Asp Ile Ser Gln Pro Leu Ser Lys Val Gly Gly Val Ile Val Glu 435 440 445 Val Asn Ala Ala Pro Gly Phe Arg Met His Thr Asn Pro Ser Gln Gly 450 455 460 Ile Ala Arg Asn Val Ala Glu Pro Val Leu Asn Met Leu Phe Pro Pro 465 470 475 480 Gly Thr Pro Cys Arg Ile Pro Ile Phe Ala Ile Thr Gly Thr Asn Gly 485 490 495 Lys Thr Thr Thr Thr Arg Leu Ile Ala His Ile Cys Lys Gln Thr Gly 500 505 510 Gln Thr Val Gly Tyr Thr Thr Thr Asp Gly Ile Tyr Ile Gly Asp Tyr 515 520 525 Leu Val Glu Lys Gly Asp Thr Thr Gly Pro Gln Ser Ala Gln Leu Ile 530 535 540 Leu Gln Asp Pro Thr Val Glu Ile Ala Val Leu Glu Thr Ala Arg Gly 545 550 555 560 Gly Ile Leu Arg Ser Gly Leu Gly Phe Asp His Cys Asp Val Gly Val 565 570 575 Val Leu Asn Val Gln Ala Asp His Leu Gly Leu Gly Asp Ile Asp Thr 580 585 590 Val Glu Gln Leu Ala Asp Leu Lys Ala Val Val Val Glu Ser Ala Trp 595 600 605 Pro Asn Gly Tyr Ala Val Leu Asn Ala Asp Asp Pro Leu Val Ala Ala 610 615 620 Met Ala Arg Gln Val Lys Ala Gln Val Ala Tyr Phe Ser Met Asp Pro 625 630 635 640 His Asn Pro Ile Ile Arg Gln His Ile Gln Gln Gly Gly Leu Ala Ala 645 650 655 Val Tyr Glu Asn Gly Tyr Leu Ser Ile Leu Lys Gly Asp Trp Thr Leu 660 665 670 Arg Ile Glu Gln Ala Glu Asn Val Pro Ile Thr Leu Gly Ala Arg Ala 675 680 685 Ser Phe Met Ile Ala Asn Ala Leu Ala Ala Ser Leu Ala Ala Phe Ala 690 695 700 Gln Gly Ile Ser Ile Glu His Ile Arg Ala Ala Leu Thr Thr Phe Arg 705 710 715 720 Thr Ser Val Glu Gln Thr Pro Gly Arg Met Asn Leu Phe Asp Leu Gly 725 730 735 Gln Phe Ser Val Leu Val Asp Tyr Ala His Asn Pro Ala Gly Tyr Glu 740 745 750 Ala Ile Gly Glu Phe Val Gln Lys Trp Pro Gly Gln Arg Ile Gly Val 755 760 765 Val Gly Gly Pro Gly Asp Arg Arg Asp Gln Asp Leu Glu Gln Leu Gly 770 775 780 Glu Leu Ser Ala Lys Ile Phe Asp Trp Ile Ile Ile Lys Glu Asp Asp 785 790 795 800 Asp Thr Arg Gly Arg Pro Arg Gly Asp Ala Ala Tyr Trp Ile Glu Arg 805 810 815 Gly Val His His His Ser Val Gln Arg Gln Tyr Asp Ile Ile His Asp 820 825 830 Glu Val Ala Ala Ile Gln Phe Ala Leu Asp Arg Ala Pro Lys Gly Ser 835 840 845 Leu Val Val Ile Phe Pro Ala Glu Val Ser Arg Thr Ile Gln Leu Ile 850 855 860 Arg Gln His His Gln Arg Leu Gln Gly Glu Thr Ile Asn Gly Phe His 865 870 875 880 Ser Glu Gly Arg Pro Thr Ser Gly Asp Leu Asn Pro Ser Ile Phe His 885 890 895 2 2691 DNA Synechococcus elongatus CDS (1)..(2691) cphA (cyanophycin synthetase) 2 atg aag att ctc aaa tta caa acg ctg cgg ggt ccc aat tac tgg agc 48 Met Lys Ile Leu Lys Leu Gln Thr Leu Arg Gly Pro Asn Tyr Trp Ser 1 5 10 15 att cgg cgt cat aag ctg att gtc atg cgt tta gat cta gaa gag gtg 96 Ile Arg Arg His Lys Leu Ile Val Met Arg Leu Asp Leu Glu Glu Val 20 25 30 gcc aac acc ccc tcc aat cag att tct ggg ttt gtg gat ggg ttg gtg 144 Ala Asn Thr Pro Ser Asn Gln Ile Ser Gly Phe Val Asp Gly Leu Val 35 40 45 cgg gtt ttg ccg agt ctt tac aat cat ttt tgt tct ctc gga cac gaa 192 Arg Val Leu Pro Ser Leu Tyr Asn His Phe Cys Ser Leu Gly His Glu 50 55 60 ggg ggc ttt ctc acc cgc ctc cga gaa ggt acg tat ctt ggt cat gtg 240 Gly Gly Phe Leu Thr Arg Leu Arg Glu Gly Thr Tyr Leu Gly His Val 65 70 75 80 gtt gaa cat gtt gcc ctc gag ctc caa gaa ctg gca ggg atg ccc gtt 288 Val Glu His Val Ala Leu Glu Leu Gln Glu Leu Ala Gly Met Pro Val 85 90 95 ggc ttt ggc cgc acg cgg gag acc tca acg ccg ggg gtg tat caa gtg 336 Gly Phe Gly Arg Thr Arg Glu Thr Ser Thr Pro Gly Val Tyr Gln Val 100 105 110 gtc tat gaa tac caa gtg gaa gaa gcg ggc cgc tat gcc ggc cga gca 384 Val Tyr Glu Tyr Gln Val Glu Glu Ala Gly Arg Tyr Ala Gly Arg Ala 115 120 125 gca gtg cga ctg tgc caa agt att att gat acg ggt acc tat ccc cag 432 Ala Val Arg Leu Cys Gln Ser Ile Ile Asp Thr Gly Thr Tyr Pro Gln 130 135 140 caa gaa ctg gat cag gat ctc gcc gat ctc cgg gag ttg aaa gca aaa 480 Gln Glu Leu Asp Gln Asp Leu Ala Asp Leu Arg Glu Leu Lys Ala Lys 145 150 155 160 gcc tcc ctt ggc ccg agt acg gaa gcg att gtc cgc gaa gcc gaa gcc 528 Ala Ser Leu Gly Pro Ser Thr Glu Ala Ile Val Arg Glu Ala Glu Ala 165 170 175 cgc aac atc cct tgg ttt gag ttg agc agt cgc tcg att att caa ttg 576 Arg Asn Ile Pro Trp Phe Glu Leu Ser Ser Arg Ser Ile Ile Gln Leu 180 185 190 ggc tat ggc gcc cgc agt cat cgg atg caa gcc aca ttg agc gat cgc 624 Gly Tyr Gly Ala Arg Ser His Arg Met Gln Ala Thr Leu Ser Asp Arg 195 200 205 agt agc atc ttg gca gtt gaa ctc gcc agt gac aaa gaa ggg gca aag 672 Ser Ser Ile Leu Ala Val Glu Leu Ala Ser Asp Lys Glu Gly Ala Lys 210 215 220 cga ctg ctt cag gat gcg gga att ccc gtg cct aag gga acc gtc atc 720 Arg Leu Leu Gln Asp Ala Gly Ile Pro Val Pro Lys Gly Thr Val Ile 225 230 235 240 cgc tat att gaa gac ctc ccc gag gcc att gag gag atc ggt ggc tat 768 Arg Tyr Ile Glu Asp Leu Pro Glu Ala Ile Glu Glu Ile Gly Gly Tyr 245 250 255 ccc att gtc att aag ccc ctc aac ggc aac cac ggt cgc ggg att acg 816 Pro Ile Val Ile Lys Pro Leu Asn Gly Asn His Gly Arg Gly Ile Thr 260 265 270 att gac atc aac agc cta gaa gca gcc gaa gaa gcc ttt gaa att gcc 864 Ile Asp Ile Asn Ser Leu Glu Ala Ala Glu Glu Ala Phe Glu Ile Ala 275 280 285 agc agc atc tcc aaa tcc gtc att gtg gaa cgc tat cat gcc ggt cgc 912 Ser Ser Ile Ser Lys Ser Val Ile Val Glu Arg Tyr His Ala Gly Arg 290 295 300 gac ttc cgc gtt cta gtg gtc aat ggc aaa gtg gtt gct gtt gct gaa 960 Asp Phe Arg Val Leu Val Val Asn Gly Lys Val Val Ala Val Ala Glu 305 310 315 320 cgg gtg ccg gcc cat gtg att ggc gat ggc cac tcc acc atc gaa gaa 1008 Arg Val Pro Ala His Val Ile Gly Asp Gly His Ser Thr Ile Glu Glu 325 330 335 ctc att gag aaa acg aac caa gac ccg caa cgg gga gac ggt cac gat 1056 Leu Ile Glu Lys Thr Asn Gln Asp Pro Gln Arg Gly Asp Gly His Asp 340 345 350 aat atc ctc acc cgc att gaa gtc aac cac gac act tgg aca ctc ctg 1104 Asn Ile Leu Thr Arg Ile Glu Val Asn His Asp Thr Trp Thr Leu Leu 355 360 365 gaa aaa cag ggc tat acc ctg aat acg gtc ttg caa ccg ggg gaa att 1152 Glu Lys Gln Gly Tyr Thr Leu Asn Thr Val Leu Gln Pro Gly Glu Ile 370 375 380 tgt tat cta cgg gcc acg gcg aac cta agt act ggt ggc att gcc atc 1200 Cys Tyr Leu Arg Ala Thr Ala Asn Leu Ser Thr Gly Gly Ile Ala Ile 385 390 395 400 gat cgc act gat gaa att cac ccg gaa aat gtt tgg att tgc cag cgg 1248 Asp Arg Thr Asp Glu Ile His Pro Glu Asn Val Trp Ile Cys Gln Arg 405 410 415 gct gct cgg atc att ggc ctc gat att gct ggt att gac gtt gtc agc 1296 Ala Ala Arg Ile Ile Gly Leu Asp Ile Ala Gly Ile Asp Val Val Ser 420 425 430 ccc gat att agt cag ccc ctg tct aaa gtt ggc ggt gtg att gtc gag 1344 Pro Asp Ile Ser Gln Pro Leu Ser Lys Val Gly Gly Val Ile Val Glu 435 440 445 gtc aat gcc gct cct ggc ttt cgc atg cac acc aac ccc agc caa ggg 1392 Val Asn Ala Ala Pro Gly Phe Arg Met His Thr Asn Pro Ser Gln Gly 450 455 460 att gcc cgc aat gtt gcc gaa ccg gtg ttg aat atg ctc ttt cca ccg 1440 Ile Ala Arg Asn Val Ala Glu Pro Val Leu Asn Met Leu Phe Pro Pro 465 470 475 480 gga aca cct tgc cgc atc ccg atc ttt gcc att acg ggg acc aat ggc 1488 Gly Thr Pro Cys Arg Ile Pro Ile Phe Ala Ile Thr Gly Thr Asn Gly 485 490 495 aaa acc acc acc acc cgt ctc att gcc cat atc tgc aaa caa acg ggg 1536 Lys Thr Thr Thr Thr Arg Leu Ile Ala His Ile Cys Lys Gln Thr Gly 500 505 510 caa acc gtt ggc tac acc acc aca gac ggc atc tat att ggc gat tat 1584 Gln Thr Val Gly Tyr Thr Thr Thr Asp Gly Ile Tyr Ile Gly Asp Tyr 515 520 525 ctg gtg gaa aaa gga gac acc acc ggc ccc caa agt gcc caa ctg atc 1632 Leu Val Glu Lys Gly Asp Thr Thr Gly Pro Gln Ser Ala Gln Leu Ile 530 535 540 ctg cag gac ccc acc gtt gag atc gcc gtt ctc gaa acg gcg cga ggt 1680 Leu Gln Asp Pro Thr Val Glu Ile Ala Val Leu Glu Thr Ala Arg Gly 545 550 555 560 ggg att ctc cgc tcc ggc ttg ggc ttt gac cat tgt gat gtc ggg gtg 1728 Gly Ile Leu Arg Ser Gly Leu Gly Phe Asp His Cys Asp Val Gly Val 565 570 575 gtg ctc aat gtg cag gct gat cac ctt ggc ctt ggc gat att gac acc 1776 Val Leu Asn Val Gln Ala Asp His Leu Gly Leu Gly Asp Ile Asp Thr 580 585 590 gtt gag cag ttg gcg gac tta aag gca gtg gtg gtg gaa tct gct tgg 1824 Val Glu Gln Leu Ala Asp Leu Lys Ala Val Val Val Glu Ser Ala Trp 595 600 605 cca aat ggc tac gct gtg ttg aat gcc gat gat ccc cta gtg gcg gca 1872 Pro Asn Gly Tyr Ala Val Leu Asn Ala Asp Asp Pro Leu Val Ala Ala 610 615 620 atg gca cgc caa gtc aaa gct caa gtg gcc tat ttc tcg atg gat ccc 1920 Met Ala Arg Gln Val Lys Ala Gln Val Ala Tyr Phe Ser Met Asp Pro 625 630 635 640 cac aat ccc atc att cgg cag cac atc cag cag ggg gga ctc gcc gct 1968 His Asn Pro Ile Ile Arg Gln His Ile Gln Gln Gly Gly Leu Ala Ala 645 650 655 gtt tat gaa aat ggc tac ctc tca att ttg aaa ggg gac tgg aca ctg 2016 Val Tyr Glu Asn Gly Tyr Leu Ser Ile Leu Lys Gly Asp Trp Thr Leu 660 665 670 cgc att gag cag gca gaa aat gtg ccc att acc ctt ggc gct cga gca 2064 Arg Ile Glu Gln Ala Glu Asn Val Pro Ile Thr Leu Gly Ala Arg Ala 675 680 685 agc ttt atg att gcc aat gcc ctc gct gcc agt cta gcg gcc ttt gcc 2112 Ser Phe Met Ile Ala Asn Ala Leu Ala Ala Ser Leu Ala Ala Phe Ala 690 695 700 caa ggc atc agt att gag cat att cgc gcc gcc ttg acc acc ttc cga 2160 Gln Gly Ile Ser Ile Glu His Ile Arg Ala Ala Leu Thr Thr Phe Arg 705 710 715 720 acc tcg gtg gag caa acc ccc ggt cgg atg aac ctc ttt gat ttg ggg 2208 Thr Ser Val Glu Gln Thr Pro Gly Arg Met Asn Leu Phe Asp Leu Gly 725 730 735 caa ttt agt gtc ttg gtg gac tat gcc cac aat cca gca ggg tat gaa 2256 Gln Phe Ser Val Leu Val Asp Tyr Ala His Asn Pro Ala Gly Tyr Glu 740 745 750 gcc att ggt gaa ttt gtc cag aaa tgg cca ggg cag cgc att ggt gtc 2304 Ala Ile Gly Glu Phe Val Gln Lys Trp Pro Gly Gln Arg Ile Gly Val 755 760 765 gtt ggc gga cca ggc gat cgc cgc gat caa gac ttg gag caa ctg ggg 2352 Val Gly Gly Pro Gly Asp Arg Arg Asp Gln Asp Leu Glu Gln Leu Gly 770 775 780 gaa ctc tcg gcg aaa att ttt gat tgg atc atc att aag gaa gat gat 2400 Glu Leu Ser Ala Lys Ile Phe Asp Trp Ile Ile Ile Lys Glu Asp Asp 785 790 795 800 gat acc cgt ggc cgg cct cgg ggc gat gcc gcc tat tgg att gag cgg 2448 Asp Thr Arg Gly Arg Pro Arg Gly Asp Ala Ala Tyr Trp Ile Glu Arg 805 810 815 ggg gta cat cac cac agt gtc cag cgg caa tac gac atc atc cat gac 2496 Gly Val His His His Ser Val Gln Arg Gln Tyr Asp Ile Ile His Asp 820 825 830 gag gtg gca gcg att caa ttt gcc ctc gat cgc gct ccc aaa gga tcc 2544 Glu Val Ala Ala Ile Gln Phe Ala Leu Asp Arg Ala Pro Lys Gly Ser 835 840 845 tta gtg gtg atc ttt cca gcg gaa gtc agc cgc acg att caa ctg att 2592 Leu Val Val Ile Phe Pro Ala Glu Val Ser Arg Thr Ile Gln Leu Ile 850 855 860 cgc cag cat cac caa cga ctc caa ggg gaa acg atc aat ggc ttt cac 2640 Arg Gln His His Gln Arg Leu Gln Gly Glu Thr Ile Asn Gly Phe His 865 870 875 880 agt gag gga agg ccc acc agt ggt gat ctc aac ccc tcc atc ttt cat 2688 Ser Glu Gly Arg Pro Thr Ser Gly Asp Leu Asn Pro Ser Ile Phe His 885 890 895 tag 2691

Claims

We claim:

1. A cyanophycin synthetase comprising an amino acid sequence according to SEQ ID No: 01, encoded by a nucleotide sequence according to SEQ ID No: 02, an allele, homologue or derivative of said nucleotide sequence or a nucleotide sequence hybridizing therewith, and originating from Synechococcus elongatus, wherein said cyanophycin synthetase has a temperature optimum of at least 35.degree. C.

2. A vector comprising at least one nucleotide sequence coding for a cyanophycin synthetase according to claim 1 or 19, which is specific for cyanophycin production.

3. A transformed unicellular or multicellular organism comprising a cyanophycin synthetase according to claim 19 and/or a vector according to claim 2.

4. A transformed unicellular or multicellular organism according to claim 3, wherein said organism is selected from the group consisting of a microorganism, a fungus, a lower or higher plant, tissue or at least one cell therefrom.

5. A method for providing a cyanophycin synthetase according to claim 1 or 19, comprising the steps of operatively linking said nucleotide sequence coding for said cyanophycin synthetase to regulatory structures and/or is cloning said nucleotide sequence into a vector suitable for heterologous expression, transferring said nucleotide sequence into a heterologous host system and expressing and isolating and/or purifying and/or concentrating said cyanophycin synthetase from said host system.

6. A method for producing cyanophycin and the secondary products to be produced therefrom, comprising the step of employing a cyanophycin synthetase according to claim 1 or 19 and/or a vector according to claim 2 and/or a transformed unicellular or multicellular organism according to any of claims 3 and 4 to produce said cyanophycin.

7. A method for preparing a transformed unicellular or multicellular organism according to either of claims 3 and 4 comprising the step of employing a vector according to claim 2 to produce said transformed organism.

8. A method for producing a compound selected from the group consisting of a cyanophycin synthetase according to claim 1 or 19 and cyanophycin comprising the steps of providing the transformed unicellular or multicellular organism according to any of claims 3 to 4, whereupon said organism produces said cyanophycin synthetase and/or said cyanophycin.

9. A method for producing cyanophycin comprising the steps of providing said cyanophycin synthetase according to claim 1 or 19, and employing said cyanophycin synthetase to produce said cyanophycin.

10. Isoenzymes and modified forms of cyanophycin synthetase wherein said isoenzymes and said modified forms of cyanophycin synthetase are obtained by modifying cyanophycin synthetasefrom Synechococcus elongatus and wherein said iso enzymes and modified forms of cyanophycin synthetase have a temperature optimum in the range of 35.degree. C. to 55.degree. C.

11. The isoenzymes and the modified forms of cyanophycin synthetase according to claim 10, wherein said isoenzymes and said modified forms of cyanophycin synthetase are obtained by amino acid exchange.

12. The isoenzymes and the modified forms of cyanophycin synthetase according to claim 11, wherein the amino acid exchange is carried out by modifying a nucleotide sequence of an underlying gene of said Synechococcus elongatus.

13. An artificial DNA sequence, comprising an artificial DNA sequence that is insertable into or appendable to a gene wherein said artificial DNA sequence encodes for and expresses the cyanophycin synthetase according to claim 1 or 19.

14. A probe for the identification and/or isolation of one or more genes coding for proteins involved in cyanophycin biosynthesis, said probe comprising a label suitable for detecting cyanophycin synthetase and modifications thereof according to claims 1 and 10.

15. A heterologous host system comprising a nucleic acid sequence or a part thereof coding for a member of the group consisting of cyanophycin synthetase, an isoenzyme and modified forms thereof according to claims 1, 19 or 10.

16. A method for the synthesis of polyaspartic acid or arginine comprising the steps of providing said cyanophycin synthetase according to claim 1 or 19 and employing said cyanophycin synthetase to produce said polyaspartic acid or said arginine.

17. Cyanophycin synthetase comprising a DNA sequence selected from the group consisting of a natural DNA sequence and an artificial DNA sequence, said DNA sequence being located between the 5' or upstream and/or 3' or downstream position of the cyanophycin synthetase according to claim 1, wherein said DNA sequences influence transcription, RNA stability of RNA processing, and translation.

18. The synthetase of claim 1 wherein said synthetase has a temperature optimum in the range of about 35.degree. C. to about 55.degree. C.

19. The synthetase of claim 1 wherein said synthetase has a temperature optimum in the range of 35.degree. C. to 55.degree. C.

20. The synthetase of claim 1 wherein said synthetase has a temperature optimum in the range of 35.degree. C. to 50.degree. C.

21. A polypeptide having cyanophycin synthetase functionality comprising a cyanophycin synthetase having a temperature optimum of at least 35.degree. C. and wherein at least one amino acid sequence of said polypeptide has been altered such that said polypeptide is rendered insensitive to the regulating action of regulatory compounds that would otherwise regulate the activity of said polypeptide with respect to said polypeptide's cyanophycin synthetase functionality.

22. The polypeptide of claim 21 wherein said cyanophycin synthetase is a cyanophycin synthetase according to claims 1 or 19.